Apparatus and microchip for sorting micro particles

ABSTRACT

In one example embodiment, a micro-particle sorting apparatus includes: (a) a microchip in which a flow path through which liquid containing a micro particle flows and an orifice through which the liquid flowing through the flow path is discharged into a space outside the chip; (b) an oscillating element for transforming the liquid into a liquid drop and discharging the liquid drop at the orifice; (c) a charge means for adding an electric charge to the discharged liquid drop; (d) an optical detection means that detects an optical property of the micro particle flowing through the flow path, upstream of a liquid-delivering direction with respect to the orifice; (e) paired electrodes opposed to each other while sandwiching the moving liquid drop along a movement direction of the liquid drop discharged into the space outside the chip; and (f) two containers that collect the liquid drop passing between the paired electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage of International ApplicationNo. PCT/JP2010/000775 filed on Feb. 9, 2010, which claims priority toJapanese Patent Application No. 2009-034337, filed in the JapanesePatent Office on Feb. 17, 2009, the entire contents of which are beingincorporated herein by refernce.

BACKGROUND

The present invention relates to an apparatus and a microchip forsorting micro particles. More specifically, the present inventionrelates to a micro-particle sorting apparatus and the like, that detectsproperties of micro particles, which flow through a flow path formed ina microchip, within the chip, discharges liquid drops containing themicro particles to the outside of the chip, and controls the movementdirections of the liquid drops on the basis of the detected propertiesof the micro particles for sorting.

Conventionally, in order to identify properties of micro particles suchas biologically-relevant micro particles such as cells, microorganisms,liposomes or synthetic particles such as latex particles, gel particles,or industrial particles, there has been utilized an apparatus thatintroduces dispersion liquid of the micro particles into the flow path,and optically measures the properties of the micro particles that havebeen introduced into the flow path.

In particular, regarding the biologically-relevant micro particles,there has been widely used an apparatus called a flow cytometry (flowcytometer) (see Non-Patent Document 1). As flow cytometries, there arethose that are designed only for measurement of the properties of themicro particles, or those that are configured to be capable of sortingonly the micro particles each having a predetermined property on thebasis of the measurement result. Regarding the latter, particularly anapparatus for a cell being as a sorting target is called “cell sorter.”The cell sorter currently available in the market is capable ofmeasuring and sorting properties of cells at high speed, for example,several thousands to several tens thousands of cells per second.

In the conventional flow cytometry, properties of the size, thestructure, and the like of the micro particles such as cells or microbeads are measured in the following manner. First, in a flow cell,sample solution containing micro particles being as measurement targetis caused to flow into the center of a laminar flow of sheath liquid, tothereby arrange the micro particles in line in the flow cell. Next, inan optical detection portion, the micro particles arranged and flowingin the flow cell are irradiated with measurement light, and scatteringlight or fluorescence generating from the micro particles is detected.In this manner, the properties of the micro particles are measured.Subsequently, in a case where the sorting of the micro particles isperformed, the sample liquid is discharged into a space outside the flowcell as liquid drops containing the micro particles, and movementdirections of the liquid drops are controlled, to thereby sort the microparticles each containing a predetermined property.

Patent Document 1 (FIG. 7) discloses an apparatus, as the conventionalcell sorter, which includes a fluid system for arranging cells stainedwith fluorescent labeling reagent or the like in line in the flow cell,and a sorting system for controlling the movement directions of theliquid drops discharged into the space outside the flow cell.

Each of those conventional flow cytometries (cell sorters) cannot beeasily disposed of by a user because the flow cell part constituting theflow path system is made of expensive quartz and is constituted of theorifice part separate from the flow cell. Thus, even if the flow cellpart and the orifice part are sufficiently washed in every measurement,there is a fear that cross contamination of samples between measurementsoccur. Further, the space constituting the sorting system is set as anopen space or a space having low air tightness, and hence contaminationmaterials such as micro liquid drops (aerosol) generating duringformation of the liquid drops may be mixed into a sample at the time ofmeasurement, or biohazard such as infection or exposure with respect toapparatus users due to the aerosol may occur. The cross contaminationbetween the samples, the contamination of the sample, the biohazard withrespect to the users, and the use of the flow cell and the orifice part,which are expensive, as described above remain obstacles particularly ina case of using stem cells or the like, which have been sorted by thecell sorter, for regenerative medicine.

As a technique for addressing the cross contamination between thesamples, the contamination of the sample, the biohazard with respect tothe users, and the use of the flow cell and the orifice part, which areexpensive, there has been, in recent years, developed a microchipincluding a silicon or glass substrate on which an area for performing achemical and biological analysis and a flow path are provided. Theanalysis system using such a microchip is called μ-TAS(micro-total-analysis system), lab-on-a-chip, biochip, or the like.

As an example of applying the μ-TAS to the micro-particle sortingtechnique, there is a micro-particle sorting technique of optically,electrically, or magnetically analyzing the properties of the microparticles in the flow path or the area provided on the microchip. Forexample, Patent Document 2 discloses a micro-particle classifyingmicrochip including, on a substrate, a micro-particle-containingsolution introducing flow path, a sheath flow forming flow path arrangedin at least one side portion of that flow path, a micro-particlemeasuring location for measuring the introduced micro particles, and twoor more micro-particle classifying flow paths for classifying andcollecting the micro particles, which are placed downstream with respectto the micro-particle measuring location. This microchip includeselectrodes near the opening of the flow path from the micro-particlemeasuring location to the micro-particle classifying flow paths.According to the micro-particle sorting apparatus including thismicrochip, it is possible to control the movement directions of themicro particles due to interaction with respect to the electric field ofthe electrodes, to thereby sort the micro particles.

In the flow cytometry (cell sorter) applying the μ-TAS, the microchipenabling a disposable use (which is disposable) can constitute the flowpath system. Therefore, the cross contamination of the samples betweenmeasurements does not occur. Further, the sorting system can be arrangedin the airtight flow path provided in the chip. Therefore, nocontamination material such as the aerosol is mixed into the sampleduring measurement. However, it is necessary to deliver at high pressurethe liquid containing the micro particles through the flow path providedin the chip. Further, it is necessary to perform the control of themovement directions of the micro particles in such a state that themicro particles are flowing in the liquid. Therefore, it is difficult toincrease the flowing velocity of the micro particles and the sortingspeed, and to measure and sort the properties of the cells at highspeed, for example, several thousands to several tens thousands of cellsper second as in the conventional flow cytometry (cell sorter).

[Cited Document]

[Patent Document]

Patent Document 1: Japanese Patent Application Laid-open No. 2007-46947

Patent Document 2: Japanese Patent Application Laid-open No. 2003-107099

[Non-Patent Document]

Non-Patent Document 1: Hiromitsu Nakauchi: Supplementary Volume of CellTechnology, Experimental Protocol Series, Master of Flow Cytometry,Shujunsha, second edition, published at 31 Aug. 2006

SUMMARY Problem to be Solved by the Invention

As described above, in the conventional flow cytometry (cell sorter),the flow cell constituting the flow path system is not configured to bedisposable, and hence there is a fear that cross contamination betweensamples occurs. Further, the space constituting the sorting system isset as an open space or a space having low air tightness, and hence thesample may be contaminated by the aerosol or the like. Further, even inthe flow cytometry (cell sorter) applying the μ-TAS, it is difficult toincrease the flowing velocity of the micro particles and the sortingspeed, and hence there is a problem that it is difficult to achieve ahigh-throughput analysis.

In view of this, it is a main object of the present invention to providea micro-particle sorting apparatus capable of performing a high-speedanalysis and a safe, high-speed, inexpensive sorting by eliminating thecross contamination between the samples, the contamination of thesample, biohazard with respect to the users, and the use of the flowcell and the orifice part, which are expensive.

Means for solving the Problem

In order to solve the above-mentioned problems, the present inventionprovides a micro-particle sorting apparatus including: a microchip inwhich a flow path through which liquid containing a micro particle flowsand an orifice through which the liquid flowing through the flow path isdischarged as a liquid drop into a space outside the chip are provided;an oscillating element for transforming the liquid into the liquid dropand discharging the liquid drop at the orifice; a charge means foradding an electric charge to the discharged liquid drop; an opticaldetection means that detects an optical property of the micro particleflowing through the flow path, upstream of a liquid-delivering directionwith respect to the orifice; paired electrodes provided so as to beopposed to each other while sandwiching the moving liquid droptherebetween along a movement direction of the liquid drop dischargedinto the space outside the chip; and two or more containers that collectthe liquid drop passing between the paired electrodes, in which a widthof the flow path and a depth of the flow path at a location of theorifice are set to be smaller than a width of the flow path and a depthof the flow path at a location at which the optical property of themicro particle is detected by the optical detection means, or in which across-section area of the flow path at a location of the orifice is setto be smaller than a cross-section area of the flow path at a locationat which the optical property of the micro particle is detected by theoptical detection means.

This micro-particle sorting apparatus may include a micro tube thatintroduces, into a laminar flow of liquid T flowing through the flowpath, a laminar flow of another liquid S containing the micro particle,upstream of the liquid-delivering direction with respect to the locationat which the optical property of the micro particles is detected by theoptical detection means.

Further, this micro tube can be configured as the charge means byforming the micro tube of a metal on which voltage can be applied.

In this micro-particle sorting apparatus, it is preferred that at leastthe orifice portion of the microchip and the space in which the liquiddrop discharged outside through the orifice moves be arranged in acavity of the cartridge having light transmittance for light from theoptical detection means.

In addition, it is preferred that the cavity of this cartridge beconfigured to be hermetically sealed.

The present invention further provides a microchip, in which a flow paththrough which liquid containing a micro particle flows and an orificethrough which the liquid flowing through the flow path is dischargedinto a space outside the chip are provided, a predetermined location ofthe flow path is configured as a light-irradiated portion to beirradiated with light from an optical detection means for detecting anoptical property of the micro particle flowing therethrough, a microtube that introduces, into a laminar flow of liquid T flowing throughthe flow path, a laminar flow of another liquid S containing microparticle, upstream of the liquid-delivering direction with respect tothe light-irradiated portion is provided, and a width of the flow pathand a depth of the flow path at a location of the orifice are set to besmaller than a width of the flow path and a depth of the flow path atthe light-irradiated portion, or a cross-section area of the flow pathat a location of the orifice is set to be smaller than a cross-sectionarea of the flow path at the light-irradiated portion.

This microchip may include an oscillating element for transforming theliquid into a liquid drop and discharging the liquid drop at theorifice.

In the microchip, it is preferred that the micro tube be formed of ametal on which voltage can be applied.

The present invention further provides a cartridge which has a cavity inwhich at least the orifice portion of the microchip according to claim10 and the space in which the liquid drop discharged outside through theorifice moves are configured, and has light transmittance with whichlight from the optical detection means is caused to transmit to thelight-irradiated portion.

It is preferred that the cavity of this cartridge be configured to behermetically sealed.

Effects of the Invention

According to the present invention, it is possible to provide themicro-particle sorting apparatus capable of performing the high-speedanalysis and the safe, high-speed, inexpensive sorting by eliminatingthe cross contamination between the samples, the contamination of thesample, the biohazard with respect to the users, and the use of the flowcell and the orifice part, which are expensive.

Additional features and advantages of the present invention aredescribed herein, and will be apparent from, the following DetailedDescription and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

[FIG. 1] A view showing a schematic configuration of a micro-particlesorting apparatus A according to the present invention.

[FIG. 2] A view showing a schematic configuration of the micro-particlesorting apparatus A.

[FIG. 3] A view showing schematic configurations of a microchip 1 and anoscillating element 2.

[FIG. 4] Sectional schematic views describing a structure of a flow path11 in vicinity of a provision location of a micro tube 16 and a limiterportion 17, and a state of a sample-liquid laminar flow and asheath-liquid laminar flow, which pass therethrough.

[FIG. 5] Sectional schematic views describing a structure of the flowpath 11 in vicinity of a pressure-rising portion 13 and an orifice 12,and the sample-liquid laminar flow and the sheath-liquid laminar flow,which pass therethrough.

[FIG. 6] A view schematically showing the sample liquid and the sheathliquid, which are transformed into liquid drops and discharged throughthe orifice 12.

[FIG. 7] Sectional schematic views describing the width and the depth ofthe flow path 11. FIG. 7A shows a cross-section of the flow path 11 atan opening position of the micro tube 16, FIG. 7B shows a cross-sectionof the flow path 11 at a light-irradiated portion 33, FIG. 7C shows across-section of the flow path 11 at a location of the orifice 12.

[FIG. 8] Views describing another preferred embodiment with respect tothe width and the depth of the flow path 11.

[FIG. 9] A view schematically showing sorting of the micro particles bythe micro-particle sorting apparatus A.

[FIG. 10] A view describing a first embodiment of a cartridge accordingto the present invention.

[FIG. 11] A view describing a second embodiment of the cartridgeaccording to the present invention.

[FIG. 12] A view describing a third embodiment of the cartridgeaccording to the present invention.

[FIG. 13] A view describing a fourth embodiment of the cartridgeaccording to the present invention.

DETAILED DESCRIPTION

Hereinafter, a preferred mode for carrying out the invention will bedescribed with reference to the drawings. It should be noted that anembodiment to be described below shows one example of a typicalembodiment of the present invention, and shall not be construed to limitthe scope of the present invention. It should be noted that thedescription will be made in the following order.

-   1. Micro-particle sorting apparatus-   2. Microchip-   (1) Flow path-   (2) Micro tube and limiter portion-   (3) Light-irradiated portion-   (4) Pressure-rising portion and orifice-   3. Oscillating element-   4. Width and Depth of flow path at each location of microchip-   5. Operation of micro-particle sorting apparatus-   6. Cartridge

1. Micro-Particle Sorting Apparatus

FIG. 1 is a view showing a schematic configuration of a micro-particlesorting apparatus according to the present invention. In the drawing,the micro-particle sorting apparatus denoted by the symbol A is mainlyconstituted of a cartridge 7 including a microchip 1 as a component andof an apparatus main body including an optical detection means 3 thatradiates the light to a predetermined location of the microchip 1. Themicrochip 1 is in such a state that one part thereof is exposed to theoutside of the cartridge and the other part is housed within thecartridge 7. In the inside of the cartridge 7, a pair of pairedelectrodes 4, 4 are provided. Further, to a side in opposite to themicrochip 1, of the cartridge 7, three containers (numerals 51, 52, 53)are connected so that the inside of each container is in communicationwith the cavity of the cartridge. The cartridge 7 includes the microchip1, the paired electrodes 4, 4, and the containers 51 to 53 as componentsis detachably attached to the main body of the micro-particle sortingapparatus A. In the main body of the micro-particle sorting apparatus A,during attachment of the cartridge 7, an oscillating element (not shown)is provided at a position at which it is brought into contact with apart of the microchip 1.

A configuration of the micro-particle sorting apparatus A will bedescribed in detail with reference to FIG. 2. FIG. 2 is a view showingthe schematic configuration of the micro-particle sorting apparatus A.The drawing shows the microchip 1 and the optical detection means 3, thepaired electrodes 4, 4, and the containers 51 to 53 which are describedabove. In the drawing, the numeral 2 denotes the oscillating elementprovided so as to be brought into contact with the part of the microchip1 during attachment of the cartridge 7 to the main body of themicro-particle sorting apparatus A. Further, the numerals 6, 6 denotegrounding paired electrodes that have been grounded. It should be notedthat here, the illustration of the cartridge 7 is omitted.

In the microchip 1, there is formed a flow path 11 through which liquid(sample liquid) containing micro particles being as sorting targetsflows. The optical detection means 3 radiates light (measurement light)to a predetermined location of the flow path 11, and detects light(measurement target light) generating from the micro particles flowingthrough the flow path 11. Hereinafter, in the flow path 11, the locationto be irradiated with the measurement light from the optical detectionmeans 3 is referred to as a “light-irradiated portion.”

The microchip 1 can be formed of glass or various type of plastics (PP,PC, COP, PDMS, for example). The material of the microchip is desirablymaterial having transmittance for the measurement light radiated fromthe optical detection means 3 and low autofluorescence and causing smalloptical error due to its small wavelength dispersion.

Formation of the flow path 11 in the microchip 1 can be performed by wetetching or dry etching with respect to a glass substrate, or bynano-imprinting, injection molding, or machining with respect to aplastic substrate. The microchip 1 can be formed by sealing a substrate,on which the flow path 11 and the like have been formed, with asubstrate made of the same material or a different material.

The optical detection means 3 can be configured similarly to theconventional flow cytometry. Specifically, the optical detection means 3is constituted of a laser light source, an irradiation system, and adetection system. The irradiation system is composed of collecting lens,a dichroic mirror, a bandpass filter, and the like for collecting andradiating the laser light with respect to the micro particles. Thedetection system detects the measurement target light generating fromthe micro particles due to the irradiation of the laser light. Thedetection system is, for example, constituted of a PMT (photo multipliertube) and an area-image pick-up element such as a CCD or CMOS element.It should be noted that although FIG. 2 shows the case where theirradiation system and the detection system are individually configured,the irradiation system and the detection system are configured throughthe same optical path (see FIG. 1).

The measurement target light to be detected by the detection system ofthe optical detection means 3 is light generating from the microparticles due to the irradiation of the measurement light. Themeasurement target light can be, for example, forward scatter or sidescatter, scattering light including Rayleigh scattering or Miescattering, or fluorescence. The measurement target light is convertedinto an electrical signal, and optical properties of the micro particlesare detected according to this electrical signal.

The sample liquid passing through the light-irradiated portion isdischarged through an orifice provided at one end of the flow path 11into the space outside the chip. At this time, the oscillating element 2oscillates the microchip 1 so that the sample liquid can be transformedinto liquid drops, and the liquid drops are discharged into the spaceoutside the chip. In FIG. 2, the symbol D denotes the liquid dropsdischarged into the space outside the chip.

The liquid drops D can contain the micro particles being as the sortingtargets. The paired electrodes 4, 4 are provided along movementdirection of the liquid drop discharged into the space outside the chip,and arranged so as to be opposed to each other while sandwiching each ofthe moving liquid drops therebetween. To the discharged liquid drop, anelectric charge is added by a charge means (not shown). The pairedelectrodes 4, 4 controls, with its electrical repelling force (orattracting force) with respect to the electric charge added to theliquid drop, the movement direction of the liquid drop. In this manner,the liquid drop is guided into any one of the containers 51 to 53. Itshould be noted that the containers 52 and 53 that collect the liquiddrops may be a commonly-used plastic test-tube container as shown in thedrawing or the like, or may be a sorting plate container including aplastic substrate on which 96 wells and the like are formed or the like.

As described above, the micro-particle sorting apparatus A ischaracterized in that processes up to the property detection of themicro particles by the optical detection means 3 are performed in themicrochip 1, and then, the control of the movement directions of themicro particles is performed in the space outside the chip. In themicro-particle sorting apparatus A, on the basis of the opticalproperties of the micro particles, which are detected by the opticaldetection means 3, the movement directions of the liquid drops eachcontaining the micro particle are controlled by the paired electrodes 4,4, and hence the micro particles each having a desired property can becollected by any one of the containers 51 to 53 for sorting.

It should be noted that in the micro-particle sorting apparatus A, theoptical detection means 3 may be replaced, for example, by an electricalor magnetic detection means. In a case of electrically or magneticallydetecting the properties of the micro particles, on both sides of theflow path 11, micro electrodes are provided so as to be opposed to eachother in order to measure resistance, capacitance, inductance,impedance, and value of change in electrical field between theelectrodes, or magnetization, a change in magnetic field, and the like.In this case, the sorting of the micro particles is performed on thebasis of electrical or magnetic properties of the micro particles.

Hereinafter, details of the respective components of the micro-particlesorting apparatus A and functions thereof will be described in order.First, with reference to FIGS. 3 to 8, the microchip 1 and theoscillating element 2 will be described.

2. Microchip

(1) Flow Path

FIG. 3 is a view showing schematic configurations of the microchip 1 andthe oscillating element 2. In the microchip 1, a sample inlet 15 throughwhich the sample liquid is introduced, and a sheath liquid inlet 14through which sheath liquid is introduced are formed. The sheath liquidintroduced into the sheath liquid inlet 14 branches into two directionsof the Y-axis positive and negative directions and is delivered throughthe flow path 11, caused to turn at approximately 90 degrees twicebefore convergence, and then delivered to the downstream.

(2) Micro Tube and Limiter Portion

At the location of the flow path 11, at which the sheath liquid isconverged, a micro tube 16 for introducing the sample liquid, which hasbeen introduced from the sample inlet 15, into a sheath-liquid laminarflow is provided. A sample-liquid laminar flow passes through the microtube 16 and is introduced into the sheath-liquid laminar flow that isintroduced from the sheath liquid inlet 14 and passes through the flowpath 11. With this, the sample-liquid laminar flow can be delivered tothe downstream of the flow path 11 while being surrounded with thesheath-liquid laminar flow.

The micro tube 16 is formed of a metal on which voltage can be applied,and is configured as the charge means that adds a positive or negativecharge with respect to the sheath liquid and the sample liquid flowingthrough the flow path 11. The sample liquid and the sheath liquid aretransformed into liquid drops through the orifice 12 provided at one endof the flow path 11, and the liquid drops are discharged into the spaceoutside the chip. At this time, by applying on the micro tube 16voltage, it is possible to add the positive or negative charge to theliquid drop to be discharged.

In FIG. 3, the numeral 17 denotes a limiter portion provided to the flowpath 11. The limiter portion 17 is formed so as to have a cross-sectionperpendicular to a liquid-delivering direction, which graduallydecreases in area from the upstream to the downstream of the flow path.

FIGS. 4 are sectional schematic views describing a structure of the flowpath 11 in vicinity of the provision location of the micro tube 16 andthe limiter portion 17 and a state of the sample-liquid laminar flow andthe sheath-liquid laminar flow, which pass therethrough. FIG. 4A shows ahorizontal sectional view (XY sectional view), and FIG. 4B shows avertical sectional view (ZX sectional view). In the drawing, the symbolS denotes the sample-liquid laminar flow, the symbol T denotes thesheath-liquid laminar flow, and the symbol P denotes the sorting-targetmicro particles contained in the sample liquid.

The sample-liquid laminar flow S is introduced through the micro tube 16into the sheath-liquid laminar flow T passing through the flow path 11,and then, delivered in such a state that the sample-liquid laminar flowS is surrounded with the sheath-liquid laminar flow T as shown in thedrawing (as three-dimensional laminar flow).

Sidewalls of the flow path at the limiter portion 17 are formed so thatthe space therebetween narrows in the Y-axis direction in the drawingalong the liquid-delivering direction. The limiter portion 17 has acounterbalance shape, which becomes gradually slimmer as viewed fromabove. With this shape, the limiter portion 17 limits the width of thelaminar flow of the sheath liquid and the sample-liquid in the Y-axisdirection in the drawing and delivers the laminar flow of the sheathliquid and the sample-liquid. Further, the limiter portion 17 is formedso that a bottom surface of the flow-path thereof is an inclined surfaceincreasing in height in a depth direction (Z-axis positive direction)from the upstream to the downstream. The limiter portion 17 limits alsothe width of the laminar flow in that direction.

As described above, when the sample-liquid laminar flow S forms thethree-dimensional laminar flow, surrounded with the sheath-liquidlaminar flow T, and this three-dimensional laminar flow is deliveredwith the width of the laminar flow of the three-dimensional laminar flowbeing limited, the sheath-liquid laminar flow T can be delivered in sucha state that the micro particles P are arranged in line in the limitedsample-liquid laminar flow S. Further, it is possible to determine aflowing position of the micro particle P in the flow path 11, and toaccurately radiate the measurement light from the optical detectionmeans 3 to the micro particles P.

In particular, the limiter portion 17 can limit the width of the laminarflow of the sample-liquid laminar flow S not only in the horizontaldirection of the microchip 1 (Y-axis direction of FIG. 4A), but also thevertical direction (Z-axis direction of FIG. 4B). Thus, a focus positionof the measurement light in the depth direction of the flow path 11 canbe caused to precisely correspond to the flowing position of the microparticle P. Therefore, it is possible to accurately radiate themeasurement light to the micro particles P and to obtain a highmeasurement sensitivity.

Here, it is conceivable that if the flow path 11 is formed as asufficiently slim flow path, and a micro tube 16 having a small diameteris used to introduce the sample-liquid laminar flow S into thesheath-liquid laminar flow T passing through the flow path 11, it isalso possible to form the three-dimensional laminar flow having apreviously limited laminar flow width. However, in this case, due to thesmall diameter of the micro tube 16, the micro tube 16 may get blockedby the micro particles P.

In the microchip 1, the limiter portion 17 is provided, and hence usingthe micro tube 16 having a diameter sufficiently larger than thediameter of each micro particle P contained in the sample liquid, thethree-dimensional laminar flow is formed, the width of the laminar flowcan be limited. Therefore, the problem of blocking of the micro tube 16as described above does not occur.

FIGS. 4 show a case where the micro tube 16 is provided so that itscenter is coaxially positioned with respect to the center of the flowpath 11. In this case, the sample-liquid laminar flow S is introducedinto the center of the sheath-liquid laminar flow T passing through theflow path 11. The position of the sample-liquid laminar flow S in thesheath-liquid laminar flow T can be arbitrarily set by adjusting anopening position of the micro tube 16 in the flow path 11. Further, forlimitation of the width of the laminar flow, it is sufficient that thelimiter portion 17 be formed so as to have the cross-sectionperpendicular to the liquid-delivering direction, which graduallydecreases in area from the upstream to the downstream of the flow path.The shape of the limiter portion 17 be not limited to the shape shown inFIGS. 4, and, for example, the limiter portion 17 may be formed so thatboth of the bottom surface of the flow-path and the top surface of theflow-path are as inclined surfaces in order to perform the limitation.

The inner diameter of the micro tube 16 can be appropriately setdepending on the diameter of each micro particle P being as the sortingtarget. For example, in a case where blood is used as the sample liquidand cells in the blood are analyzed, it is preferred that the innerdiameter of the micro tube 16 range from approximately 10 to 500 μm.Further, it is sufficient that the width and the depth of the flow path11 at the opening position of the micro tube 16 be appropriately setdepending on the outer diameter of the micro tube 16 reflecting thediameter of each micro particle P. For example, in a case where theinner diameter of the micro tube 16 ranges from approximately 10 to 500μm, it is preferred that each of the width and the depth of the flowpath 11 at the opening position of the micro tube 16 range fromapproximately 100 to 2000 μm. It should be noted that the shape of thecross-section of the micro tube can be an appropriate shape such as anoval shape, a quadrangle, or a triangular shape other than the circularshape.

Although the width of the laminar flow of the sample-liquid laminar flowS and the sheath-liquid laminar flow T before limitation by the limiterportion 17 can vary depending on the width and the depth of the flowpath 11 and the diameter of the micro tube 16, it is possible to limitthe width of the laminar flow into an appropriate laminar flow width byappropriately adjusting the area of the cross-section of the limiterportion 17, the cross-section being perpendicular to theliquid-delivering direction. For example, in FIG. 4B, when a length ofthe flow path at the limiter portion 17 is denoted by L and an angle ofinclination of the bottom surface of the flow-path is denoted by θ3, alimitation width of the three-dimensional laminar flow at the limiterportion 17 is L*tanθ3. Therefore, by appropriately adjusting the lengthof the flow path L and the angle of inclination θ3, an appropriatelimitation width can be set. In addition, in FIG. 4A, when narrowingangles in the Y-axis direction of sidewalls of the flow path at thelimiter portion 17 are denoted by θ1, θ2, respectively, and these anglesand the above-mentioned θ3 are set to “θ3=2×θ1, θ1=θ2,” thesample-liquid laminar flow S and the sheath-liquid laminar flow T can beisotropically reduced in size. Thus, it is possible to limit the widthof the laminar flow without disturbing the three-dimensional laminarflow formed through the micro tube 16.

(3) Light-Irradiated Portion

In FIG. 3, the numeral 33 denotes the light-irradiated portion to beirradiated with the measurement light from the optical detection means3. In the light-irradiated portion 33, the measurement target lightgenerating from each of the micro particles due to the irradiation ofthe measurement light from the optical detection means 3 is detected.

As previously mentioned, in the light-irradiated portion 33, the limiterportion 17 limits the width of the laminar flow of the sample-liquidlaminar flow and the sheath-liquid laminar flow. Therefore, it ispossible to cause the focus position of the measurement light toprecisely correspond to the flowing position of the sample-liquidlaminar flow S in the flow path 11, so that the micro particle can beaccurately irradiated with the measurement light.

The laminar flow width of the sample-liquid laminar flow S and thesheath-liquid laminar flow T at the light-irradiated portion 33 can beset to be an appropriate laminar flow width by appropriately adjustingthe area of the cross-section of the limiter portion 17, thecross-section being perpendicular to the liquid-delivering direction.Preferably, each of the width and the depth of the flow path 11 rangesfrom approximately 20 to 2000 μm.

(4) Pressure-Rising Portion and Orifice

In FIG. 3, the numeral 12 denotes the orifice for discharging the sheathliquid and the sample liquid, which have passed through thelight-irradiated portion 33, into the space outside the chip. The sheathliquid and the sample liquid are transformed into liquid drops throughthe orifice 12 due to action of the oscillating element 2 to bedescribed below and the liquid drops are discharged into the outside ofthe chip.

The numeral 13 denotes a pressure-rising portion provided upstream withrespect to the orifice 12 and downstream with respect to thelight-irradiated portion 33 in the flow path 11. The pressure-risingportion 13 is formed so as to have the cross-section perpendicular tothe liquid-delivering direction, which gradually decreases in area fromthe upstream to the downstream of the flow path. That is, similarly tothe limiter portion 17, sidewalls of the flow path are formed so thatthe space therebetween narrows in the Y-axis direction in the drawingalong the liquid-delivering direction. Further, the pressure-risingportion 13 is formed so that a bottom surface of the flow-path thereofis an inclined surface increasing in height from the upstream to thedownstream in a depth direction (Z-axis positive direction).

FIGS. 5 are sectional schematic views describing a structure of the flowpath 11 in vicinity of the pressure-rising portion 13 and the orifice12, and a state of the sample-liquid laminar flow and the sheath-liquidlaminar flow, which pass therethrough. FIG. 5A shows a horizontalsectional view (XY sectional view), and FIG. 5B shows a verticalsectional view (ZX sectional view). In the drawing, the symbol S denotesthe sample-liquid laminar flow, the symbol T denotes the sheath-liquidlaminar flow, and the symbol P denotes the sorting-target microparticles contained in the sample liquid.

The sample-liquid laminar flow S and the sheath-liquid laminar flow Tare delivered in such a state that the width of the laminar flow islimited in the Y-axis direction and the Z-axis direction in the drawingat the pressure-rising portion 13. Due to this limitation of the widthof the laminar flow, the pressure-rising portion 13 functions toincrease a liquid-delivering pressure of the sample liquid and thesheath liquid in the flow path 11, to thereby discharge them at highpressure through the orifice 12. This function of the pressure-risingportion 13 allows, during transformation into liquid drops through theorifice 12, the liquid drops to be formed at higher frequency. Thus,high speed sorting can be realized. In FIGS. 3 and 5, a movementdirection of the discharged liquid drops is denoted by the symbol F.

The laminar flow width of the sample-liquid laminar flow S and thesheath-liquid laminar flow T at the location of the orifice 12 can belimited to an appropriate laminar flow width by appropriately adjustingthe area of the cross-section of the pressure-rising portion 13, thecross-section being perpendicular to the liquid-delivering direction.For example, in FIG. 5B, when the length of the flow path at thepressure-rising portion 13 is denoted by 1, and the angle of inclinationof the bottom surface of the flow-path is denoted by θ3, the limitationwidth of the three-dimensional laminar flow at the pressure-risingportion 13 is L*tanθ3. Therefore, by appropriately adjusting the lengthof the flow path 1 and the angle of inclination θ3, an appropriatelimitation width can be set. It is preferred that regarding the width ofthe laminar flow of the sample-liquid laminar flow S and thesheath-liquid laminar flow T at the location of the orifice 12, each ofthe width and the depth at the location of the orifice 12 range fromapproximately 20 to 500 μm.

It should be noted that limitation of the width of the laminar flow ofthe sample-liquid laminar flow S and the sheath-liquid laminar flow Tmay be performed in such a manner that both of the bottom surface of theflow-path and the top surface of the flow-path at the pressure-risingportion 13 is set as inclined surfaces, and the shape of thepressure-rising portion 13 is not limited to the shape shown in thedrawing. These points are the same as in the case of the limiter portion17. Further, in FIG. 5A, when narrowing angles in the Y-axis directionof sidewalls of the flow path at the pressure-rising portion 13 aredenoted by θ1, θ2, respectively, and the narrowing angle θ3 in theZ-axis direction are set to “θ3=2×θ1, θ1=θ2,” the three-dimensionallaminar flow formed through the micro tube 16 can be isotropicallyreduced in size. Thus, it is possible to limit the width of the laminarflow without disturbing the three-dimensional laminar flow formedthrough the micro tube 16. This point is also the same as describedabove with respect to the limiter portion 17.

3. Oscillating Element

In FIG. 3, the numeral 2 denotes the oscillating element that is broughtinto contact with the part of the microchip 1 during attachment of thecartridge 7 to the main body of the micro-particle sorting apparatus A(see FIG. 1). Here, a case of providing the oscillating element 2 on themain body side of the micro-particle sorting apparatus A will bedescribed. However, the oscillating element 2 may be provided integrallywith the chip as an inner component of the microchip 1.

The oscillating element 2 oscillates the microchip 1 at a predeterminedfrequency, to thereby transform the sample liquid and the sheath liquidinto liquid drops and discharge the liquid drops at the orifice 12. Thetransformation into liquid drops of the sample liquid and the sheathliquid using the oscillating element as described above can be performedin the same manner as that of the conventional a flow cytometry usingflow cell. The oscillating element 2 is constituted of, for example, apiezo oscillating element also adopted in an ink-jet printer or thelike.

FIG. 6 is a view schematically showing the sample liquid and the sheathliquid, which are transformed into liquid drops and discharged throughthe orifice 12. The sample-liquid laminar flow S containing the microparticles P is transformed into liquid drops through the orifice 12together with the sheath-liquid laminar flow T and discharged as liquiddrops D to the arrow F direction in the drawing.

The oscillating element 2 oscillates the microchip 1 at a predeterminedfrequency, to thereby transform the sample liquid and the sheath liquidinto liquid drops in such a manner that each of the discharged liquiddrop D contains each of the micro particles P as shown in the drawing.At this time, the frequency of the oscillating element 2 is setdepending on a flowing speed (flow velocity) of the micro particles Pand a liquid-delivering pressure to be detected by the optical detectionmeans 3 at the light-irradiated portion 33, oscillating frequency of themicrochip 1, and the like. Further, the frequency of the oscillatingelement 2 can be set also depending on the width and the depth of theflow path 11 at the location of the orifice 12 (that is, area ofvertical cross-section).

4. Width and Depth of Flow Path at each Location of Microchip

FIGS. 7 are sectional schematic views describing the width and the depthat each location of the flow path 11. The drawing shows a YZcross-section of the flow path 11. FIG. 7A shows the opening position ofthe micro tube 16, FIG. 7B shows the light-irradiated portion 33, andFIG. 7C shows the cross-section of the flow path 11 at the location ofthe orifice 12.

As shown in FIG. 7A, at the opening position of the micro tube 16, thesample-liquid laminar flow S and the sheath-liquid laminar flow T aredelivered as the three-dimensional laminar flow in such a state that thesample-liquid laminar flow S is surrounded with the sheath-liquidlaminar flow T. As previously mentioned, the width and the depth of theflow path 11 at the opening position of the micro tube 16 isappropriately set depending on the outer diameter of the micro tube 16reflecting the diameter of each of the micro particles P, and, forexample, is set to range from approximately 100 to 2000 μm.

The three-dimensional laminar flow formed through the micro tube 16 isdelivered to the light-irradiated portion 33 in such a state that thewidth of the laminar flow is limited by the limiter portion 17 (see FIG.7B). When the limiter portion 17 limits the width of the laminar flow,the three-dimensional laminar flow is delivered to the light-irradiatedportion 33 in such a state that the micro particles P is arranged inline in the sample-liquid laminar flow S.

The laminar flow width of the sample-liquid laminar flow S and thesheath-liquid laminar flow T at the light-irradiated portion 33 can bearbitrarily set by appropriately adjusting the area of the cross-sectionof the limiter portion 17, the cross-section being perpendicular to theliquid-delivering direction. Each of the width (W) and the depth (H) ofthe flow path 11 at the light-irradiated portion 33 is set to range fromapproximately 20 to 2000 μm in order to obtain a sufficiently largeoptically-detecting angle (numerical aperture of the optical system) ofthe optical detection means 3. In this manner, the optically detectingangle δ and the numerical aperture can be sufficiently increased.

In addition, the shape of the flow path 11 at the light-irradiatedportion 33 is preferably rectangular with respect to a radiationdirection of the measurement light of the optical detection means 3through setting the width (W) to be larger than the depth (H). When theflow path 11 at the light-irradiated portion 33 is set to have such awide shape, it is possible to increase the numerical aperture of theoptical system.

The sample-liquid laminar flow S and the sheath-liquid laminar flow Tpassing through the light-irradiated portion 33 are delivered to theorifice 12 in such a state that the width of the laminar flow are againlimited by the pressure-rising portion 13 as shown in FIG. 7C. When thepressure-rising portion 13 limits the width of the laminar flow, adischarging pressure of the sample liquid and the sheath liquid throughthe orifice 12 can be increased.

The laminar flow width of the sample-liquid laminar flow S and thesheath-liquid laminar flow T at the location of the orifice 12 can bearbitrarily set by appropriately adjusting the area of the cross-sectionof the pressure-rising portion 13, the cross-section being perpendicularto the liquid-delivering direction. At the orifice 12, in order to formthe high frequency liquid drops at high speed, the width of the laminarflow of the sample-liquid laminar flow S and the sheath-liquid laminarflow T at the location of the orifice 12 is preferably set to be smallso as to sufficiently increase the discharging pressure of the sampleliquid and the sheath liquid. For this reason, the width (w) and thedepth (h) of the flow path 11 at the opening of the orifice 12 are setto be smaller than the width (W) and the depth (H) at thelight-irradiated portion 33. Otherwise, the cross-section area of theflow path 11 at the opening of the orifice 12 is set to be smaller thanthe cross-section area at the light-irradiated portion 33. Thus, it ispreferred that each of the width (w) and the depth (h) of the flow path11 at the opening of the orifice 12 be set to range from approximately20 to 500 μm.

Here, the case of first setting, by the limiter portion 17, the width ofthe laminar flow of the three-dimensional laminar flow formed throughthe micro tube 16 to be a width suitable for optical detection of themicro particles at the light-irradiated portion 33, and then setting, bythe pressure-rising portion 1, to a width with which the high-frequencyliquid drop formation is enabled has been described. The limitation ofthe width of the laminar flow in the flow path 11 does not need to beperformed in two phases of the limiter portion 17 and thepressure-rising portion 13, and, for example, as shown in FIGS. 8, canbe performed in such a manner that between the opening position of themicro tube 16 and the orifice 12 of the flow path 11, the width and thedepth of the flow path or the cross-section area of the flow pathbecome/becomes smaller continuously and gradually.

In addition to this, the shape of the flow path 11 can be set to bevarious shapes as long as the width and the depth of the flow path atthe opening position of the micro tube 16, the light-irradiated portion33, and the location of the orifice 12 fall within the above-mentionedsuitable numeral range, or as long as the cross-section area of the flowpath satisfies the above-mentioned magnitude relation.

Further, the shape of the opening of the orifice 12 can be anappropriate shape such as a square shape, a rectangular shape, or acircular shape. In addition, as shown in FIGS. 8, an end surface portionof the opening portion can be also set to be an inverse-tapered shape.When the opening end surface portion of the orifice 12 is set to be sucha trumpet shape, it is possible to achieve a smooth discharge of theformed liquid drops.

5. Operation of Micro-Particle Sorting Apparatus

Next, the operation of the micro-particle sorting apparatus A will bedescribed with reference to FIG. 9.

The sample liquid and the sheath liquid, which have passed through thelight-irradiated portion of the flow path 11, are discharged through theorifice 12 into the space outside the chip. At the light-irradiatedportion, the optical detection means detects the optical properties ofthe micro particles and at the same time detects the flowing speed (flowvelocity) of the micro particles, intervals between the micro particles,and the like. The detected optical properties of the micro particles,the flow velocity, the intervals, and the like are converted into anelectrical signal and output to a general control portion (not shown) ofthe apparatus. The general control portion controls, according to thissignal, the oscillation frequency of the oscillating element 2. In thismanner, the microchip 1 is oscillated so that each liquid drop D formedthrough the orifice 12 contains each of the micro particles P.

In addition, the general control portion controls voltage to be appliedon the micro tube 16 in synchronous with the oscillating frequency ofthe oscillating element 2, to thereby switch the positive and negativeof the electric charge to be added to the sheath liquid and the sampleliquid, which flow through the flow path 11, and add the positive ornegative charge to the liquid drop D formed through the orifice 12. Theoptical property of the micro particle, which has been detected by theoptical detection means, is converted into an electrical signal andoutput to the general control portion. The general control portioncontrols, according to this signal, voltage to be applied on the microtube 16, and determines the electric charge to be added to the liquiddrop depending on the optical property of the micro particle containedin each liquid drop. Specifically, the general control portionpositively charges, for example, the liquid drop containing thesorting-target micro particle having a predetermined property, whilenegatively charges the liquid drop containing no sorting-target microparticle.

At this time, in order to stabilize the charge state of the liquid dropD, in the micro-particle sorting apparatus A, in vicinity of the orifice12, along the movement direction of the liquid drop discharged into thespace outside the chip, grounding paired electrodes 6, 6 are arranged.The grounding electrodes 6, 6 are arranged so as to be opposed to eachother while sandwiching the moving liquid drop therebetween, and isprovided between the orifice 12 and paired electrodes 41, 42 forcontrolling the movement directions of the micro particles.

The movement direction of the liquid drop D charged and dischargedthrough the orifice 12 is controlled due to the electrical force actingbetween the paired electrodes 41, 42. At this time, in order toprecisely control the movement direction, it is necessary that a stableelectric charge be added to the liquid drop in advance. On the pairedelectrodes 41, 42, significantly high voltage is applied, and hence highpotential of the paired electrodes 41, 42 may influence the electriccharge to be added at the orifice 12 through the micro tube 16 to theliquid drop D. In this case, there is a fear that the charge state ofthe liquid drop D lacks the stability. In view of this, in themicro-particle sorting apparatus A, the grounding electrodes 6, 6 areprovided while being grounded between the orifice 12 and the pairedelectrodes 41, 42, to thereby eliminate such an influence due to thehigh potential of the paired electrodes 41, 42.

The control of the movement direction of the liquid drop D to bedischarged through the orifice 12 is performed in the following manner,for example. That is, in the above-mentioned example of positivelycharging the liquid drop containing the sorting-target micro particlehaving a predetermined property, and negatively charging the liquid dropcontaining no sorting-target micro particle, by positively charging thepaired electrode 41 and negatively charging the paired electrode 42,only the sorting-target micro particles can be sorted into the container53. Specifically, regarding the liquid drop containing thesorting-target micro particle to which the positive electric charge hasbeen added, the movement direction thereof is controlled to the arrow f3direction and this liquid drop is guided into the container 53 due toelectrical repelling force with respect to the paired electrode 41 andelectrical attraction force with respect to the paired electrode 42.Meanwhile, regarding the liquid drop containing no sorting-target microparticle to which the negative electric charge has been added, themovement direction thereof is controlled to the arrow f2 direction andthis liquid drop is guided into the container 52.

Alternately, for example, if no electric charge is added to the liquiddrop containing the sorting-target micro particle having a predeterminedproperty, and the liquid drop containing no sorting-target microparticle is positively or negatively charged, the paired electrodes 41,42 are positively or negatively charged, only the sorting-target microparticles can be sorted into the container 51. In addition to this, thecontrol of the movement direction of the liquid drop by using theelectric charge to be added to the liquid drop D and the pairedelectrodes 41, 42 can be performed in various combinations similarly tothe conventional flow cytometry. It should be noted that two or morecontainers for collecting the liquid drops D, and the number ofcontainers is not limited to three. In addition, those containers may beconfigured as discharge channels that discharge the collected liquiddrops without storing, or the collected micro particles not being as thesorting target may be set to be disposable.

Here, the case where with respect to the liquid drop D, the positive ornegative charge is switched and added on the basis of the property ofthe micro particle contained in the liquid drop in order to performsorting has been described as an example. The sorting of the liquiddrops can be performed also by positively or negatively charging allliquid drops D, and switching voltage to be applied on the pairedelectrodes 41, 42 on the basis of the properties of the micro particles.Further, also in the case where the optical detection means is replacedby the electrical or magnetic detection means, by similarly controllingthe movement directions of the liquid drops on the basis of theelectrical or magnetic properties of the micro particles, the microparticles each having a predetermined property are collected into anyone of the containers 51 to 53 for sorting.

As described above, the sorting of the micro particles by themicro-particle sorting apparatus A is characterized in that processes upto the property detection of the micro particles by the opticaldetection means 3 are performed in the microchip 1, and then, thecontrol of the movement directions of the micro particles is performedas liquid drops discharged into the space outside the chip.

As previously mentioned, in the conventional flow cytometry using a flowcell, a flow cell part constituting a flow path system for forming alaminar flow and an orifice part for forming liquid drops are expensive,and the positions of them need to be finely adjusted (aligned) in orderto prevent the laminar flow from being disturbed. Further, they are notconfigured to be disposable, and hence there is a fear that crosscontamination between samples occur. In contrast, in the micro-particlesorting apparatus A, formation of the laminar flow and detection of theproperties of the micro particles are performed in the microchip 1, inwhich the flow cell part and the orifice part are integrated, whichenables a disposable use, and hence the cross contamination of thesamples between measurements does not occur. In addition, the alignmentas in the past becomes unnecessary, and hence it becomes possible for auser to more simply perform sorting.

Further, in the micro-particle sorting apparatus A, the control of themovement direction of the micro particle is performed in the spaceoutside the chip, and hence, without need for performing the control ofthe movement directions of the micro particles in the flowing liquid asin the conventional flow cytometry applying the μ-TAS, a higher sortingspeed can be obtained. In addition, in the micro-particle sortingapparatus A, it is possible to sufficiently increase theliquid-delivering pressure of the sample liquid and the sheath liquid inthe flow path 11, and hence to discharge through the orifice 12 highfrequency liquid drops at high speed. Thus, a high sorting speed can beobtained.

6. Cartridge

In addition, in the micro-particle sorting apparatus A, it is preferredthat the space in which the control of the movement direction of theliquid drop is performed be arranged in the cavity of the cartridge 7(see FIG. 1) that can be hermetically sealed. That is, as shown in FIG.10, at least the orifice 12 portion of the microchip 1 and the space inwhich the liquid drop D discharged through the orifice 12 to the outsideof the chip moves are desirably arranged in an airtight space in thecartridge 7. At this time, in order to prevent formation of the liquiddrop at the orifice 12 from being inhibited, the microchip 1 is attachedto the cartridge 7 in such a state that the orifice 12 portion canoscillate at a predetermined oscillation frequency due to oscillationcaused from the oscillating element 2. Specifically, it is desirablethat an end side of the microchip 1 in opposite to the orifice 12 befixed to the cartridge 7, and an orifice 12 end side of the microchip 1be not in contact with the cartridge 7.

In the cavity of the cartridge 7, the paired electrodes 4, 4 forcontrolling the movement directions of the liquid drops and thegrounding electrodes 6, 6 are provided. The containers 51 to 53 forcollecting the liquid drops are detachably attached to the cartridge 7,and are set to communicate to the cavity of the cartridge 7 in anairtight manner during attachment.

As described above, the space between the orifice 12 through which theliquid drops are discharged and the containers 51 to 53 into which theliquid drops are collected is configured as the cartridge 7 cavity thatcan be hermetically sealed, and hence it is possible to preventcontamination materials such as micro liquid drops (aerosol) and thelike generating when the liquid drops are formed through the orificefrom being mixed into the sample. Further, at the same time, the liquiddrops and the aerosol generating during formation of the liquid dropscan be confined in the cartridge 7. Thus, in a case of sorting dangerousmicro particles such as infectious cells, it is possible to prevent themfrom being exposed to the user and contaminating environment.

Desirably, the cartridge 7 is generally formed of glass or variousplastics similarly to the microchip 1, and has light transmittance forthe measurement light from the optical detection means. Alternatively,as shown in the drawing, at a position of the microchip 1, whichcorresponds to the light-irradiated portion, an optical window 34 may beprovided so that only this optical window 34 portion has transmittancefor the measurement light. Otherwise, in a case of providing the opticalwindow 34 by cutting out a part of the cartridge 7, even when objectivelens having high numerical aperture and short motion distance is used asthe optical detection means, the object lens can approach thelight-irradiated portion surface of the microchip 1. In this case,desirably, in order to prevent contamination through the opened opticalwindow, the orifice 12 end of the microchip 1 is formed to be slim, andas shown in FIG. 11, an opening being a communication hole between themicrochip 1 and the space in which the movement direction of the liquiddrop is to be controlled is set to be small. When the orifice 12 end ofthe microchip 1 is formed to be slim, it is possible to set the openingbeing the communication hole to be smaller than that in FIG. 10. Inaddition, when the orifice 12 end formed to be slim is inserted into thespace in which the movement direction of the liquid drop is to becontrolled, it is possible to increase a sealing efficiency for theliquid drops and the aerosol generating during formation of the liquiddrops.

In order to further enhance air tightness in the cartridge 7, it ispreferred that the optical window 34 be formed of a material havinglight transmittance, for example, glass. In this case, the opticalwindow 34 is formed of, for example, a material having hightransmittance, such as plastic having a surface on which anantireflective film or an antireflective nano structure or quartz. Thethickness of the optical window is formed to be as small as possible, tothereby minimize optical loss.

FIG. 12 and FIG. 13 are views showing other preferred embodiments of thecartridge 7. As shown in FIG. 12, the paired electrodes 4, 4 thatperform the control of the movement directions of the liquid drops andthe grounding paired electrodes 6, 6 may be provided on the main bodyside of the micro-particle sorting apparatus A. In this case, fittingholes are formed in the cartridge 7, and thus, during attachment to theapparatus main body, the paired electrodes 4, 4 and the grounding pairedelectrodes 6, 6 can be inserted into the fitting holes. When insertedinto the fitting holes, the paired electrodes 4, 4 and the groundingpaired electrodes 6, 6 are arranged along the movement direction of theliquid drop discharged through the orifice of the microchip 1.

Further, as shown in FIG. 13, the cartridge 7 may be provided with asample liquid reservoir 8 for supplying to the microchip 1 the sampleliquid. The sample liquid from the sample liquid reservoir 8 is suppliedthrough the sample liquid inlet 15 into the microchip 1. With this, alsowith respect to the supplying path for the sample liquid, the disposableuse can be enabled. Thus, it is possible to further prevent the crosscontamination of the samples between measurements.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

Description of Symbols

A micro-particle sorting apparatus

D liquid drop

P micro particles

S sample-liquid laminar flow

T sheath-liquid laminar flow

1 microchip

11 flow path

12 orifice

13 pressure-rising portion

14 sheath liquid inlet

15 sample liquid inlet

16 micro tube

17 limiter portion

2 oscillating element

3 optical detection means

33 light-irradiated portion

34 optical window

4, 41, 42 paired electrode

51, 52, 53 container

6 grounding electrode

7 cartridge

8 sample liquid reservoir

The invention claimed is:
 1. A micro-particle sorting apparatuscomprising: a microchip in which a flow path through which liquidcontaining a micro particle flows and an orifice through which theliquid flowing through the flow path is discharged into a space outsidethe microchip; an oscillating element configured to transform the liquidinto a liquid drop and discharge the liquid drop at the orifice; acharge means for adding an electric charge to the discharged liquiddrop; an optical detection means that detects an optical property of themicro particle flowing through the flow path, upstream of aliquid-delivering direction with respect to the orifice; pairedelectrodes provided so as to be opposed to each other while sandwichingthe moving liquid drop therebetween along a movement direction of theliquid drop discharged into the space outside the microchip; two or morecontainers that collect the liquid drop passing between the pairedelectrodes, wherein a width of the flow path and a depth of the flowpath at a location of the orifice are set to be smaller than a width ofthe flow path and a depth of the flow path at a location at which theoptical property of the micro particle is detected by the opticaldetection means; and wherein at least the orifice portion of themicrochip and the space outside the microchip in which the liquid dropdischarged through the orifice moves are arranged in a cavity of acartridge having light transmittance for light from the opticaldetection means.
 2. The micro-particle sorting apparatus of claim 1,which includes a micro tube that introduces, into a laminar flow ofliquid T flowing through the flow path, a laminar flow of another liquidS containing the micro particle, upstream of the liquid-deliveringdirection with respect to the location at which the optical property ofthe micro particles is detected by the optical detection means.
 3. Themicro-particle sorting apparatus of claim 2, wherein the micro tube isformed of a metal on which voltage can be applied and is configured asthe charge means.
 4. The micro-particle sorting apparatus of claim 1,wherein the cavity of the cartridge is configured to be hermeticallysealed.
 5. A micro-particle sorting apparatus comprising: a microchip inwhich a flow path through which liquid containing a micro particle flowsand an orifice through which the liquid flowing through the flow path isdischarged into a space outside the microchip; an oscillating elementfor transforming the liquid into a liquid drop and discharging theliquid drop at the orifice; a charge means for adding an electric chargeto the discharged liquid drop; an optical detection means that detectsan optical property of the micro particle flowing through the flow path,upstream of a liquid-delivering direction with respect to the orifice;and paired electrodes provided so as to be opposed to each other whilesandwiching the moving liquid drop therebetween along a movementdirection of the liquid drop discharged into the space outside themicrochip; and two or more containers that collect the liquid droppassing between the paired electrodes, wherein a cross-section area ofthe flow path at a location of the orifice is set to be smaller than across-section area of the flow path at a location at which the opticalproperty of the micro particle is detected by the optical detectionmeans; and wherein at least the orifice portion of the microchip and thespace outside the microchip in which the liquid discharged through theorifice moves are arranged in a cavity of a cartridge having lighttransmittance for light from the optical detection mean.
 6. A microchipcomprising: a flow path through which liquid containing a micro particleflows and an orifice through which the liquid flowing through the flowpath is discharged into a space outside the microchip; a predeterminedlocation of the flow path configured as a light-irradiated portion to beirradiated with light from an optical detection means for detecting anoptical property of the micro particle flowing therethrough; and a microtube that introduces, into a laminar flow of liquid T flowing throughthe flow path, a laminar flow of another liquid S containing microparticle, upstream of the liquid-delivering direction with respect tothe light-irradiated portion, wherein a width of the flow path and adepth of the flow path at a location of the orifice are set to besmaller than a width of the flow path and a depth of the flow path atthe light-irradiated portio; and wherein the micro tube is formed of ametal on which voltage can be applied.
 7. The microchip of claim 6,which includes an oscillating element for transforming the liquid into aliquid drop and discharging the liquid drop at the orifice.
 8. Acartridge which has a cavity in which at least the orifice portion ofthe microchip of claim 6 and the space outside the microchip in whichthe liquid drop discharged through the orifice moves are arranged,wherein the cartridge has light transmittance with which light from theoptical detection means is caused to transmit to the light-irradiatedportion.
 9. The cartridge of claim 8, wherein the cavity is configuredto be hermetically sealed.
 10. A microchip comprising: a flow paththrough which liquid containing a micro particle flows and an orificethrough which the liquid flowing through the flow path is dischargedinto a space outside the microchip; a predetermined location of the flowpath configured as a light-irradiated portion to be irradiated withlight from an optical detection means for detecting an optical propertyof the micro particle flowing therethrough; and a micro tube thatintroduces, into a laminar flow of liquid T flowing through the flowpath, a laminar flow of another liquid S containing micro particle,upstream of the liquid-delivering direction with respect to thelight-irradiated portion, wherein a cross-section area of the flow pathat a location of the orifice is set to be smaller than a cross-sectionarea of the flow path at the light-irradiated portion; and wherein themicro tube is formed of a metal on which voltage can be applied.